CSV Row Duplicator

What does the CSV Row Duplicator do?

The CSV Row Duplicator duplicates a selected row from a CSV spreadsheet a specified number of times and inserts the copies at a designated position (immediately after the original, immediately before, at the very top under the header, or at the bottom).

Core Concepts

• Exact Row Replication: Generates $N$ identical row copies preserving cell values, types, and column positioning.
• Configurable Insertion Target: Choose between after (adjacent), before, top, or bottom insertion.
• Header Isolation: Keeps the table schema and header row untouched at the top of the file.

How to use the tool?

1. Input CSV Data: Paste your CSV spreadsheet rows into the input box or click Load Sample.
2. Configure Duplication:
   • Row to Duplicate: Select the target data row from the dropdown.
   • Number of Copies: Enter the number of duplicate rows to create (e.g. 3).
   • Insert Position: Choose immediately after, before, top, or bottom.
3. Duplicate & Export: Click Duplicate Row, then click Copy or Download.

Related Developer Utilities

• CSV Row Deduplicator: Remove duplicate rows from CSV files.
• CSV Column Duplicator: Clone a single column to a new index position.
• CSV Row Filter: Filter CSV rows by comparison conditions.

REST API Integration

blueutils.com provides a free REST API endpoint (POST https://blueutils.com/api/csv/csv-row-duplicator) for programmatic integration.

API Request Parameters

API Request Payload Examples

cURL (String Payload)

curl -X POST https://blueutils.com/api/csv/csv-row-duplicator \
  -H "Content-Type: application/json" \
  -d '{
    "payload": "sku,name,price\nSKU-101,Keyboard,49.99\nSKU-102,Mouse,29.99",
    "options": {
      "rowIndex": 0,
      "count": 2,
      "position": "after"
    }
  }'

Python (Array Payload)

import requests

url = "https://blueutils.com/api/csv/csv-row-duplicator"
payload = {
    "payload": [
        ["sku", "name", "price"],
        ["SKU-101", "Keyboard", "49.99"],
        ["SKU-102", "Mouse", "29.99"]
    ],
    "options": {
        "rowIndex": 0,
        "count": 2,
        "position": "after"
    }
}
headers = {"Content-Type": "application/json"}
response = requests.post(url, json=payload, headers=headers)
print(response.json())

Java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Main {
    public static void main(String[] args) throws Exception {
        String jsonPayload = "{\"payload\": \"id,val\\n1,A\\n2,B\", \"options\": {\"rowIndex\": 0, \"count\": 2}}";
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://blueutils.com/api/csv/csv-row-duplicator"))
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(jsonPayload))
            .build();
        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.body());
    }
}

API Response Parameters

API Response Payload Examples

Success Response (HTTP 200 OK)

{
  "isValid": true,
  "result": "sku,name,price\nSKU-101,Keyboard,49.99\nSKU-101,Keyboard,49.99\nSKU-101,Keyboard,49.99\nSKU-102,Mouse,29.99",
  "data": [
    ["sku", "name", "price"],
    ["SKU-101", "Keyboard", "49.99"],
    ["SKU-101", "Keyboard", "49.99"],
    ["SKU-101", "Keyboard", "49.99"],
    ["SKU-102", "Mouse", "29.99"]
  ],
  "originalSize": 64,
  "resultSize": 116,
  "headers": ["sku", "name", "price"],
  "targetRowIndex": 0,
  "targetRowDisplayIndex": 1,
  "duplicateCount": 2,
  "position": "after",
  "originalRowCount": 2,
  "finalRowCount": 4,
  "columnCount": 3
}

Error Response (HTTP 400 Bad Request)

{
  "isValid": false,
  "error": "CSV input cannot be empty."
}

Rate Limit Exceeded Response (HTTP 429 Too Many Requests)

{
  "error": "API rate limit exceeded. Please wait or contact support@blueutils.com."
}

Why use an API to duplicate CSV rows?

Integrating the CSV Row Duplicator API into CI/CD pipelines, automated ETL pipelines, or autonomous agent workflows provides several practical advantages:

• Rapid Script Validation: Enables developers and QA engineers to quickly generate synthetic mock dataset rows and scale test fixtures programmatically.
• Optimized Token Efficiency for AI Agents: Programmatic row cloning via API completely avoids sending and regenerating thousands of repetitive CSV tokens through LLMs.
• Deterministic Accuracy Without Hallucinations: Language models can introduce subtle character distortions or increment IDs incorrectly when replicating lines. Delegating processing to a deterministic API guarantees 100% computational accuracy every time without token overhead.

Native Usage

How to achieve the same task locally without external dependencies using native operating system utilities and scripting languages:

Windows (CMD / PowerShell)

Using native PowerShell array repetition:

# Duplicate row 1 (index 1 in 0-based lines) 3 times
$lines = Get-Content -Path "input.csv"
$header = $lines[0]
$data = $lines[1..($lines.Length - 1)]
$target = $data[0]
$copies = @($target) * 3
$result = @($header, $target) + $copies + $data[1..($data.Length - 1)]
$result | Set-Content -Path "output.csv"

Linux / Unix (Bash / Shell)

Using standard Linux sed or awk:

# Duplicate line 2 three times in Bash
sed '2p;2p;2p' input.csv > output.csv

Python

Using the Python standard library csv module:

import csv

with open("input.csv", mode="r", encoding="utf-8") as infile:
    reader = csv.reader(infile)
    rows = list(reader)

# Duplicate row 1 (index 1) 3 times
if len(rows) > 1:
    target_row = rows[1]
    for _ in range(3):
        rows.insert(2, list(target_row))

with open("output.csv", mode="w", newline="", encoding="utf-8") as outfile:
    writer = csv.writer(outfile)
    writer.writerows(rows)

print("Row duplicated successfully.")

Java

Using standard Java java.nio.file.Files:

import java.nio.file.*;
import java.util.*;

public class DuplicateCsvRowExample {
    public static void main(String[] args) throws Exception {
        List<String> lines = new ArrayList<>(Files.readAllLines(Paths.get("input.csv")));
        if (lines.size() <= 1) return;

        String target = lines.get(1); // 1st data row
        int count = 3;
        for (int i = 0; i < count; i++) {
            lines.add(2, target);
        }

        Files.write(Paths.get("output.csv"), lines);
        System.out.println("Row duplicated successfully.");
    }
}